Surface activation in electrode stack production and electrode-preparation systems and methods

ABSTRACT

Methods, stacks and electrochemical cells are provided, in which the cell separator is surface-treated prior to attachment to the electrode(s) to form binding sites on the cell separator and enhance binding thereof to the electrode(s), e.g., electrostatically. The cell separator(s) may be attached to the electrode(s) by cold press lamination, wherein the created binding sites are configured to stabilize the cold press lamination electrostatically—forming flexible and durable electrode stacks. Electrode slurry may be deposited on a sacrificial film and then attached to current collector films, avoiding unwanted interactions between materials and in particular solvents involved in the respective slurries. Dried electrode slurry layers may be pressed or calendared against each other to yield thinner, smother and more controllably porous electrodes, as well as higher throughput. The produced stacks may be used in electrochemical cells and in any other type of energy storage device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-part of U.S. patent applicationSer. No. 15/431,793, filed Feb. 14, 2017 and entitled “Electrode stackproduction methods” which claims the benefit of U.S. Provisional PatentApplication No. 62/435,865, filed Dec. 19, 2016; this application alsoclaims the benefit of U.S. Provisional Patent Application No.62/537,535, filed Jul. 27, 2017, all of which are hereby incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention relates to the field of cells in energy storagedevices, and more particularly, to manufacturing of cell stacks withelectrodes and to electrode production process modifications.

2. Discussion of Related Art

Energy storage devices can be found in an increasing number ofapplications, and they diversify in structure and components. Productionprocesses of energy storage devices are complex with respect tomechanical steps and chemical considerations involved in the production.Constant demand exists for improving the performance of energy storagedevices and for improving their production processes and quality ofcomponents.

SUMMARY OF THE INVENTION

The following is a simplified summary providing an initial understandingof the invention. The summary does not necessarily identify key elementsnor limit the scope of the invention, but merely serves as anintroduction to the following description.

One aspect of the present invention provides a method comprising surfacetreating the cell separator prior to attachment to at least oneelectrode, wherein the surface treating is configured to form bindingsites on the cell separator and enhance binding thereof to the at leastone electrode by creating the binding sites.

One aspect of the present invention provides a method comprising:surface treating at least one cell separator prior to attachment to atleast one electrode, wherein the surface treating is configured to formbinding sites on the at least one cell separator, and attaching the atleast one cell separator to the at least one electrode by cold presslamination, wherein the created binding sites are configured tostabilize the cold press lamination electrostatically.

One aspect of the present invention provides a method comprisingdepositing an electrode slurry on a sacrificial film to form anelectrode thereupon, wherein the electrode slurry comprises a firstsolvent, optionally surface treating the electrode, attaching (e.g.,laminating) a current collector film, which is produced at least partlyusing a second solvent, onto the formed electrode, to yield a stack,wherein a binding strength of the electrode to the current collectorfilm is higher than a binding strength of the electrode to thesacrificial film, and delaminating the sacrificial film from theelectrode while maintaining the attachment of the electrode to thecurrent collector film.

One aspect of the present invention provides an electrode-preparationmethod comprising: pressing at least two double-sided coated currentcollector foils between external coated foils, wherein the coatings onthe double-sided foils face each other and the coatings of therespective external foils, and are pressed against each other, andpreparing electrodes from at least one of the pressed double-sidedcoated current collector foils.

One aspect of the present invention provides a method comprising surfacetreating, prior to stack lamination, at least one cell separator and/orat least one electrode, wherein the surface treating is configured toform binding sites on the at least one cell separator and/or at leastone electrode, respectively, and laminating, by cold press lamination, astack of multiple alternating separators and electrodes, comprising theat least one separator and the at least one electrode, at least one ofwhich being surface treated by said surface treating, wherein thecreated binding sites are configured to stabilize the cold presslamination electrostatically.

One aspect of the present invention provides an electrode-preparationmethod comprising: pressing at least two double-sided coated currentcollector foils between external coated foils, wherein the coatings onthe double-sided foils face each other and the coatings of therespective external foils, and are pressed against each other, andpreparing electrodes from at least one of the pressed double-sidedcoated current collector foils.

One aspect of the present invention provides a method comprisingdepositing an electrode slurry on a sacrificial film to form anelectrode thereupon, wherein the electrode slurry comprises a firstsolvent, attaching (e.g., laminating) a current collector film, which isproduced at least partly using a second solvent, onto the formedelectrode, to yield a stack, wherein a binding strength of the electrodeto the current collector film is higher than a binding strength of theelectrode to the sacrificial film, and delaminating the sacrificial filmfrom the electrode while maintaining the attachment of the electrode tothe current collector film.

These, additional, and/or other aspects and/or advantages of the presentinvention are set forth in the detailed description which follows;possibly inferable from the detailed description; and/or learnable bypractice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of embodiments of the invention and to showhow the same may be carried into effect, reference will now be made,purely by way of example, to the accompanying drawings in which likenumerals designate corresponding elements or sections throughout.

In the accompanying drawings:

FIGS. 1A-1C are high-level schematic illustrations of surface treatingthe separator in methods of stack assembly, according to someembodiments of the invention.

FIG. 2 is a high-level schematic illustration of cell stacks and theirassembly, according to some embodiments of the invention.

FIGS. 3A-3C are high-level schematic illustrations of systems andmethods of preparing electrode stacks, according to some embodiments ofthe invention.

FIGS. 4A-4C are high-level schematic illustrations of derived processesfor preparing various stacks using the method, according to someembodiments of the invention.

FIG. 5 is a high-level schematic illustration of stacks havingelectrode(s) and cell separator(s) prepared by the method, according tosome embodiments of the invention.

FIG. 6 is a high-level schematic illustration of using structures as thecurrent collector, which may be patterned, mesh-like and/or foam-like,according to some embodiments of the invention.

FIG. 7 is a high-level flowchart illustrating methods, according to someembodiments of the invention.

FIG. 8 is a high-level schematic illustration of electrode foils and anelectrode production system, according to some embodiments of theinvention.

FIG. 9 is a high-level schematic illustration of prior art electrodeproduction.

FIG. 10 is a high-level schematic illustration of electrode productionsystem, according to some embodiments of the invention.

FIGS. 11A and 11B are high-level schematic illustrations of electrodeproduction systems, according to some embodiments of the invention

FIGS. 12-16 are high-level schematic illustrations of electrodeproduction systems, according to some embodiments of the invention.

FIGS. 17A and 18A illustrate examples of cross-sections of prior artelectrode foils.

FIGS. 17B and 18B illustrate examples of cross-sections of electrodefoils prepared according to some embodiments of the invention.

FIGS. 19A-19C are examples for disclosed separators and stacks preparedaccording to disclosed methods, compared to prior art separators andstacks.

FIG. 19D is a SEM image of prior art double sided electrode (anode)produced not using the disclosed lamination process, and exhibitingrough and non-uniform anode surfaces.

FIGS. 20A and 20B are SEM images of prepared laminated separators andelectrodes, according to some embodiments of the invention.

FIG. 21 provides SEM images of the surfaces of anodes, cathodes andseparators before and after surface treatment by plasma, in anon-limiting example, according to some embodiments of the invention.

FIGS. 22A-22C illustrate prior art cell assembly with its cyclingcharacteristics; and cycling characteristics of laminated stacksillustrated in FIG. 19A, in a non-limiting example, according to someembodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, various aspects of the present inventionare described. For purposes of explanation, specific configurations anddetails are set forth in order to provide a thorough understanding ofthe present invention. However, it will also be apparent to one skilledin the art that the present invention may be practiced without thespecific details presented herein. Furthermore, well known features mayhave been omitted or simplified in order not to obscure the presentinvention. With specific reference to the drawings, it is stressed thatthe particulars shown are by way of example and for purposes ofillustrative discussion of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

Before at least one embodiment of the invention is explained in detail,it is to be understood that the invention is not limited in itsapplication to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention is applicable to other embodiments that may bepracticed or carried out in various ways as well as to combinations ofthe disclosed embodiments. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

Methods, stacks and electrochemical cells are provided, in which thecell separator is surface-treated prior to attachment to theelectrode(s) to form binding sites on the cell separator and enhancebinding thereof to the electrode(s), e.g., electrostatically, to improvecontact and reduce resistance of the layers in the formed battery cellstack.

Methods, stacks and electrochemical cells are provided, in which thecell separator is surface-treated prior to attachment to theelectrode(s) to form binding sites on the cell separator and enhancebinding thereof to the electrode(s), e.g., electrostatically. The cellseparator(s) may be attached to the electrode(s) by cold presslamination, wherein the created binding sites are configured tostabilize the cold press lamination electrostatically—forming flexibleand durable electrode stacks. Electrode slurry may be deposited on asacrificial film and then attached to current collector films, avoidingunwanted interactions between materials and in particular, solventsinvolved in the respective slurries. Dried electrode slurry layers maybe pressed or calendared against each other to yield thinner, smotherand more controllably porous electrodes, as well as higher throughput.The produced stacks may be used in electrochemical cells and in anyother type of energy storage device.

Methods, stacks and electrochemical cells are provided, which improveproduction processes and yield flexible and durable electrode stacks.Methods comprise depositing an electrode slurry on a sacrificial film toform an electrode thereupon, wherein the electrode slurry comprises afirst solvent, attaching (e.g., laminating) a current collector film,which is produced at least partly using a second solvent that may be thesame or different from the first solvent, onto the formed electrode, toyield a stack, wherein a binding strength of the electrode to thecurrent collector film is higher than a binding strength of theelectrode to the sacrificial film, and delaminating the sacrificial filmfrom the electrode while maintaining the attachment of the electrode tothe current collector film. Additional layers such as a cell separatorand an additional electrode may be further attached using similar steps.Surface treatment of electrodes and/or separator further enhances thecell performance. The produced stacks may be used in electrochemicalcells and in any other type of energy storage device.

Certain embodiments comprise cell stacks for lithium ion batteries,which comprise multiple stacked anodes and cathodes, separated by cellseparator(s), with at least one of the anodes, the cathodes and the cellseparators being surface treated to form binding sites upon surfacesthereof, and with the anodes, the cathodes and the cell separators beingattached by cold press lamination, which is electrostatically stabilizedby the created binding sites.

Electrode-preparation methods and systems are provided, in which coatedfoils, e.g., having dried electrode slurry layers on one or both sidesof current collector films, are pressed against each other, with coatinglayers on the films facing each other and pressing each other.Particularly in lithium ion battery anodes made of metalloid anodematerial particles, the hardness of the particles may provide moreefficient pressing when pressed against each other, than when pressed byan external calendar—leading to thinner, smother and more controllablyporous electrodes and higher throughput. Two or more double-sided coatedcurrent collector foils may be pressed between external (possiblysacrificial) coated foils, with the coatings on the double-sided foilsface each other and the coatings of the respective external foils.Electrodes (e.g., anodes, cathodes) may be prepared from the presseddouble-sided coated current collector foils.

FIGS. 1A-1C are high-level schematic illustrations of surface treating aseparator 75 in methods of stack assembly, according to some embodimentsof the invention. Elements from FIGS. 1A-1C may be integrating in any ofthe following embodiments involving the stack's separator(s).

FIG. 1A illustrates schematically the formation of binding sites 105A ona separator 75, which enhance the binding of separator 75 toelectrode(s) 95 by creating bond(s) with surface elements 105B onelectrode(s) 95, such as oxides exposed on the surface of electrode 95,upon attachment or during the stack preparation processes.Advantageously, surface treatment 105 provides better attachment oftreated surface 105A to electrode(s) 95 than untreated surface 61 (shownschematically, the numeral 61 is used to denote untreated prior artseparators), in particular for separator(s) 75 comprising polymers suchas any of polyethylene (PE), polypropylene (PP), polyethyleneterephthalate (PET), poly vinylidene fluoride (PVDF), polymer membranessuch as a polyolefin, polypropylene, or polyethylene membrane.Multi-membranes made of these materials, micro-porous films thereof,woven or non-woven fabrics etc. may be used as separator(s) 75 as wellas possibly composite materials including, e.g., alumina, zirconia,titania, magnesia, silica and calcium carbonate along with variouspolymer components as listed above. For example, binding sites 105A maycomprise oxygen termination of surface molecules such as carboxylates,hydroxyls, etc. which may react electrostatically with oxides exposed onthe surface of electrode(s) 95, e.g., under pressure, when pressedagainst each other.

In certain embodiments, surface treatment 105 may be applied to one orboth sides of electrode(s) 95 (e.g., anodes and/or cathodes) to formsurface elements 105B thereupon, which them bind electrostatically tobinding sites 105A on separator 75 upon cell assembly, such as upon coldpressing the stack assembly.

FIG. 1B is a high-level schematic illustration of a cell stack assemblysystem 150, according to some embodiments of the invention. System 150may be used to implement any of the embodiments of the disclosedmethods, and may be composed modularly from the following units,according to specifically required battery stack compositions andperformance.

Cell stack assembly system 150 may comprise a surface treatment module152 configured to treat one or both surfaces (possibly patch-wise) ofeach of a plurality of cell separators 75 (and possibly of electrode(s)95), to form binding sites thereupon; a stacking module 154 configuredto stack a plurality of alternating anodes and cathodes (as electrodes95) between cell separators 75 to form a stack 100; and a cold-presslamination module 156 configured to cold-press stack 100, wherein theformed binding sites are configured to stabilize the cold-pressed stackelectrostatically. Cold-press lamination module 156 is configured topress stack 100 to form a laminated stack 108 which may be used to forma battery cell 109.

In certain embodiments, cell stack assembly system 150 may furthercomprise a layer transfer module 160 (see, e.g., FIGS. 3A-6) configuredto prepare electrode(s) 95 attached to corresponding current collectorfilm(s) by depositing electrode slurry on a sacrificial film to formelectrode(s) 95 thereupon. The electrode slurry comprises a firstsolvent, the current collector film is produced using a second solvent,and is attached onto the formed electrode. The binding strength of theelectrode to the current collector film is higher than a bindingstrength of the electrode to the sacrificial film. Layer transfer module160 is further configured to delaminate the sacrificial film from theelectrode while maintaining the attachment of the electrode to thecurrent collector film.

In certain embodiments, cell stack assembly system 150 may furthercomprise a pressing or calendaring unit 170 (see, e.g., FIGS. 8 and10-18B) comprising two pressure-applying apparatuses facing each otherand configured to receive and press, against each other, at least twodouble-sided coated current collector foils between external coatedfoils. The coatings on the double-sided foils face each other and thecoatings of the respective external foils, and are pressed against eachother. The two pressure-applying apparatuses are configured to applypressure on the external coated foils to make the electrodes moreuniform (with respect to electrodes press directly against thecalendars. The external coated foils may also comprise electrode films(with electrode slurry coating(s)).

In various embodiments, pressing or calendaring unit 170 may beconfigured to operate at optimized parameters of pressure, time andoptionally heat application. Pressing or calendaring unit 170 may beconfigured to adjust the porosity of electrode(s) 95 and in someembodiments, as part of the lamination process, attach separator(s) 75to electrode(s) 95, utilizing surface treatment 105 applied to separator75 and/or electrode(s) 95 to generate stable laminated stack 108. Incertain embodiments, electrode porosity may thus be optimized duringattachment in a single (pressing or calendaring) step, wherein theattachment is assisted by surface treatment 105. It is noted that eitherprior art calendaring (see e.g., FIG. 9) and/or disclosed calendaringprocesses according to various embodiments (see, e.g., FIGS. 8 and10-16) may be used in embodiments of the production process, and incombination with surface treatment 105.

FIG. 1C illustrates schematically an example for stack assembly,utilizing rollers 106 of electrode foils (anode foil(s) 95A, cathodefoil(s) 95B) and of separator foil(s) 75 and integrating the foils intoa stack using additional rollers 107 (illustrated schematically) invarious configurations—yielding stacks 100. Stack assembly processes,into which separator surface treatment may be integrated, comprise anyof the following—single sheet stacking, winding, Z-folding with singleelectrodes, Z-folding with electrode rolls, and so forth, as explainedin more details below. Surface treatment 105 may be applied to eitherside of separator patches or foils, continuously or intermittently,depending on the spatial relations of the respective side of separator75 with electrode 95 it is designed to bind, e.g., anode 95A. Stackassembly may be carried out in electrode production system(s) 150,possibly comprising electrode and stack preparation systems and methods,and possibly pressure-applying apparatuses as disclosed below.

Certain embodiments comprise methods 200 disclosed below, stack assemblysystems 150 and/or laminated stacks 108, comprising surface treating105, prior to stack lamination, at least one cell separator 75 and/or atleast one electrode 95, wherein surface treating 105 is configured toform binding sites on the at least one cell separator and/or at leastone electrode, respectively, and laminating, by cold press lamination, astack of multiple alternating separators and electrodes, comprising theat least one separator and the at least one electrode, at least one ofwhich being surface treated by surface treating 105, wherein the createdbinding sites are configured to stabilize the cold press laminationelectrostatically. The alternating separators and electrodes may beattached by any stack assembly process, such as single sheet stacking,winding, Z-folding with single electrodes and/or Z-folding withelectrode rolls, and the surface treatment may be carried out by any ofplasma treatment, corona treatment, ultraviolet radiation. The stack ofmultiple alternating separators and electrodes may comprise any of: asingle separator and a single electrode, a single separator and twoelectrodes on either side thereof, a single electrode and two separatorson either side thereof and/or an alternating plurality of separators andplurality of electrodes. In a non-limiting example, the stack ofmultiple alternating separators and electrodes may comprise a singleseparator foil and two electrodes foils which are laminated to on eitherside of the separator foil by a roll to roll process.

FIG. 2 is a high-level schematic illustration of cell stacks 100 andtheir assembly, according to some embodiments of the invention. FIG. 2illustrates schematically cell stack 100 in exploded view and,correspondingly, the structure of laminated stack 108 after cold-presslamination 156 (illustrated schematically by arrows). Optional processesof applying optional coatings 82, 92 and 77 to electrodes 95 (anodes95A, cathodes 95B and corresponding current collectors 80A, 80B) (seeFIGS. 3A-6 and corresponding description below), layer transferring 160(e.g., by corresponding module 160), pressing or calendaring 170 (ofone-another-facing electrodes, e.g., by corresponding unit 170) may bepart of the stack assembly. The dotted arrow indicates the optionalstacking of multiple sets of separators 75 and electrodes 95 to formstack 100.

In certain embodiments, multiple separators 75 and correspondingmultiple alternating anodes and cathodes may be assembled into cellstack 100. In various embodiments, both the anode(s) and the cathode(s)may be attached to separator(s) 75 simultaneously by the cold pressing.The cold-press lamination may be carried out below any of 60° C. (e.g.,as in the example below, at 55° C.), 50° C., 40° C. and/or at roomtemperatures, and surface treatment 105 may be carried out (be surfacetreating unit 152) by any of plasma treatment, corona treatment,ultraviolet radiation and/or possibly by depositing an ionic-conductivesurface layer to form binding sites 105A.

In certain embodiments, cell separator(s) 75 may be polymeric (asdisclosed above) and surface treatment 105 may comprise depositing aceramic surface layer onto polymeric cell separator 75. As illustratedschematically in FIG. 2, surface treatment 105 may be configured tomodify only treated surface 75A while maintaining the bulk properties ofseparator(s) 75 such as ionic conductivity of bulk 75B of separator(s)75, possibly flexibility of separator(s) 75, interaction properties withthe electrolyte etc. Treated surface 75A may be porous andion-conductive, to maintain and/or enhance the performance of cell stack108. Cold-press lamination 156 may be configured to ensure close contactbetween separator(s) 75 and electrode(s) 95.

Lamination of separator(s) 75 and electrode(s) 95 may be configured toreduce the resistance of laminated cell stack 108 and battery 109 withrespect to prior art stack assembly methods, due to the close contactbetween separator(s) 75 and electrode(s) 95, based on the disclosedelectrostatic binding. In certain embodiments, laminated cell stack 108and battery 109 may be advantageous in fast charging applications, inwhich lower resistance is of particular advantage. Examples for fastcharging applications comprise battery cells 109 configured to operateand high charging and/or discharging rates such as e.g., at least at amaximal charging and/or discharging rate of e.g., 5 C, or possibly 10 Cor 50 C, or higher, with the C rate, or C ratio, being the charging ordischarging current divided by the capacity.

Any of the disclosed systems and methods may be applied to anodes havingSi (silicon), Ge (germanium), Sn (tin) and/or LTO (lithium titaniumoxide, lithium titanate)-based anode active material and/or possiblycarbon-based anode material such as graphite and/or graphene. Thedisclosed systems and methods may be applied to cathodes comprisematerials based on layered, spinel and/or olivine frameworks, havingvarious compositions, such as LCO formulations (based on LiCoO₂), NMCformulations (based on lithium nickel-manganese-cobalt), NCAformulations (based on lithium nickel cobalt aluminum oxides), LMOformulations (based on LiMn₂O₄), LMN formulations (based on lithiummanganese-nickel oxides), LFP formulations (based on LiFePO₄), lithiumrich cathodes, and/or combinations thereof. The disclosed systems andmethods may be applied to electrolyte comprising liquid electrolytessuch as ethylene carbonate (EC), diethyl carbonate (DEC), propylenecarbonate (PC), fluoroethylene carbonate (FEC), ethyl methyl carbonate(EMC), dimethyl carbonate (DMC), vinylene carbonate (VC), possiblytetrahydrofuran (THF) and/or its derivatives, and combinations thereofand/or solid electrolytes such as polymeric electrolytes such aspolyethylene oxide, fluorine-containing polymers and copolymers (e.g.,polytetrafluoroethylene), and combinations thereof. The electrolyte(s)may comprise lithium electrolyte salt(s) such as LiPF₆, LiBF₄, lithiumbis(oxalato)borate, LiN(CF₃SO₂)₂, LiN(C₂F₅SO₂)₂, LiAsF₆, LiC(CF₃SO₂)₃,LiClO₄, LiTFSI, LiB(C₂O₄)₂, LiBF₂(C₂O₄), tris(trimethylsilyl)phosphite(TMSP) and combinations thereof. Electrolyte additive(s) (e.g., at few %wt) may comprise tris(trimethylsilyl)phosphite (TMSP), tris(trimethylsilyl) borate (TMSB), lithium difluoro(oxalato)borate (LiFOB),succinic anhydride, trimethyl phosphate (TMP) and triphenyl phosphate(TFP), fluorinated solvents (methyl nonafluorobutyl ether (MFE), andcombinations thereof.

FIGS. 3A-3C and 4A-4C are high-level schematic illustrations of system160 and method 200 of preparing electrode stacks 100, according to someembodiments of the invention. Elements from FIGS. 3A-3C and 4A-4C may becombined in any operable combination and the illustration of certainelements in certain figures and not in others merely serves anexplanatory purpose and is non-limiting. Layer transferring may becarried out by layer transfer module 160 of cell stack assembly system150.

FIGS. 3A-3C exemplify schematically the attachment of respectiveelectrodes 95, namely an anode 95A and a cathode 95B, to respectivecurrent collector films 80, namely a copper (Cu) film 80A and analuminum (Al) film 80B, respectively. Electrodes 95A, 95B (FIG. 3A) mayfirst be formed on respective sacrificial films 90, namely a copper foil90A and aluminum foil 90B, respectively, from respective electrodeslurries involving certain solvents. Then, electrodes 95 on sacrificialfilms 90 are attached (220) to the corresponding current collector films80 and sacrificial films 90 are delaminated (222) to yield respectivestacks 100, namely anode-current collector stack 100A andcathode-current collector stack 100B, respectively. In certainembodiments, respective coatings 82, such as carbon and/or binder layers82A, 82B may be applied to current collector films 80 prior toattachment 220 to enhance binding and/or improve the stack's operation.The binding strength of electrode 95 to current collector film 80 (withor without coating 82) is configured to be higher than the bindingstrength of electrode 95 to sacrificial film 90. In certain embodiments,layer 82 may comprise a thin carbon coating (e.g., ˜1 μm thick) or aconductive adhesive. FIGS. 3B and 3C illustrate additional attachmentmodes disclosed below. Elements shown separately in FIGS. 3A-3C, and inother figures, may be combined to form various embodiments of thedisclosed invention.

The inventors have found out that direct application of the electrodeslurry on the current collector film often results in interactionsbetween the solvents used to form the electrode slurry and solventswhich were used in production of the current collector film and/ordegradation of current collector 80 due to solvent ingredients. Eventhough these interactions may be useful for the enhancement of bindingstrength between the current collector and the electrode coating, theseinteractions, if excessive, may deteriorate the performance of therespective prior art electrodes and the prior art cells having theseelectrodes. Furthermore, during and after the electrode slurryapplication onto the current collector in the prior art, problemsrelated to the poor wettability of the current collector by theelectrode slurry may arise. These problems may result in coating defectsand poor adhesion of the resulting coating to the current collector.However, the inventors have found out that forming the electrode of thesacrificial film and then transferring the electrode as disclosed hereinto the current collector film solve these problems and provide flexibleelectrode stacks with improved performance. Moreover, disclosedembodiments may provide sufficient binding strength between the currentcollector and the electrode coating.

In certain embodiments, the surface of one or more of electrodes 95(e.g., anode 95A, cathode 95B) may be pretreated 105 to enhance itsadhesion to current collector film 80 (with or without coating 82). Incertain embodiments, with uncoated current collector film 80, thesurface of one or more of current collector film 80 (e.g., Cu film 80Aor Al film 80B) may be pretreated 105 to enhance its adhesion torespective electrode(s) 95. In certain embodiments, coated films mayalso be pre-treated to enhance the respective binding to adjacent layer.Achieved adhesion enhancement may improve the integration of therespective layer and provide more uniform and compact cell structures,resulting in improved electrolyte wetting, cell conductivity (e.g.,reduce ESR—equivalent series resistance) and other cell characteristics.For example, plasma treatment 105 may be applied to activate therespective surface(s) prior to pressing the respective layers, toenhance their attachment (e.g., lamination) by resulting electrostaticforces between the activated surface and the layer connected thereto.Surface treatment 105, such as by plasma, may be configured to affectonly the surface and not deteriorating the bulk properties of thetreated layer, and may additionally improve wetting and ionicconductivity of the treated surface.

The electrode slurry may comprise a water or organic solvent, activematerial(s), conductive agent(s) and/or binder(s), and be dried, e.g.,by evaporation of the solvent, to form electrode 95 on sacrificial film90 prior to its attachment to current collector 80. Attachment 220 maybe carried out by bringing electrode 95 into close contact with currentcollector 80 which may be coated by an adhesive conductive layer coatingfacing electrode 95. As the surface of current collector 80 may beundesirably altered by an excessive interaction with the solvent of theelectrode slurry, allowing the solvent to at least partially evaporateprior to the attachment prevents or at least significantly reduces suchan excessive interaction. The attachment may be carried out in alamination process. Sacrificial film 90 may be delaminated 222 fromelectrode 95 after attachment 220, e.g., by peeling it off theelectrode, leaving behind stack 100 with current collector 80 attachedto electrode 95, which exhibits highly improved adhesion, cohesion andflexibility.

Method 200 enables fabrication of mechanically strong and flexibleelectrodes for energy storage devices. Advantageously, disclosed method200 provides any of the following: improved adhesion (bonding ofelectrode 95 to current collector 80), improved cohesion (e.g., inelectrode 95, bonding between active material, conductive additiveparticles and binder), improved flexibility of electrode 95, decreasedbinder content in electrode 95, and method 200 prevents the undesirableinteraction of current collector 80 and/or adhesive layer 82 with slurrysolvents, thus preventing the wettability issues or corrosion of currentcollector 80 which are typical in the prior art.

Advantageously, method 200 may be configured to further enablemitigation and/or avoid wettability problems as compared with the directcoating of the electrode slurry onto the current collector, carried outin the prior art. For example, common prior art practice is to use NMP(N-methyl-2-pyrrolidone) as the solvent in the electrode slurry, howeverNMP may attack carbon coating 82 on current collector film 80 until theslurry has dried. As a result, carbon coating 82 may not functionproperly.

As the risk of solvent influence on current collector 80 is reduced,selection and optimization of active materials, binders and conductiveagents in the electrode slurry may be carried out to a larger extent.The formulation of the slurry may be selected to ensure the optimizedpacking density and related porosity of electrode 95 to provide optimalenergy and power density of the energy storage device.

Sacrificial film 90 may comprise a metal foil and/or a polymeric foil orfilm. Sacrificial film 90 may comprise an anti-adhesive coating 92 thatmakes the transfer process easy. In particular, coating 92 (and/orcoating 82) may be selected so that the binding strength of electrode 95to current collector film 80 (possibly via coating 82) is higher thanthe binding strength of electrode 95 to sacrificial film 90 (possiblyvia coating 92), as indicated schematically in FIG. 3B.

Current collector film 80 may be made of various materials (e.g., copperor aluminum) and may be formed as a foil, a film, a grid or any otherconfiguration. Coating 82 may be an adhesive conductive coating, such asa mixture of conductive particles (for example, carbon black, graphite,graphene or metal particles) and polymeric binder (for example, PVDF(polyvinylidene difluoride), PTFE (polytetrafluoroethylene), acrylicresins, elastomers, water-soluble polymers and the likes). At least oneof the binders used in the electrode slurry and in the adhesive coatingmay be configured to increase the adhesiveness between electrode 95 andcurrent collector film 80, in certain embodiments, under influence oftemperature and/or pressure during attachment (e.g., lamination) stage220 and possibly in delamination 222 stage, due to, for example,thermoplastic properties of the respective binder polymer. In certainembodiments, surfaces of electrode 95 and/or current collector film 80and/or coating 82 may be wetted by an appropriate solvent to increaseadhesive property, transferability and/or conformability. FIG. 3Cillustrates schematically the optional wetting 91 of the interfacebetween electrode 95 and sacrificial film 90 (possibly as a residualsolvent from the electrode slurry), wetting 96 of electrode 95 and/orwetting 81 of current collector film 80 and/or coating 82.

Attachment 220 may be carried out by lamination, e.g., by hot rollpress, followed by separation of respective copper or aluminum foils90A, 90B respectively as delamination 222.

The following are more detailed examples for preparing anode stack 100Aand cathode stack 100B. Anode stack 100A was prepared from a water-basedanode slurry comprising carbon/tin composite as the active material,carbon black as the conductive agent and CMC (carboxymethyl cellulose)as the binder onto a copper foil substrate as sacrificial film 90. Thethickness was controlled by using a doctor blade with 50 μm, 100 μm and120 μm gaps. Coated samples were dried in a convection oven for one hourat 80° C. to evaporate the solvent and form electrode 95 on coppersacrificial film 90. In a tape test using an adhesive tape, asignificant portion of the coating (electrode 95) was removed with thetape, as a simulator for current collector film 80. After the coatedsamples were crumpled, electrode coating flaked off (delaminated) fromthe copper substrate. For preparation of stack 100A, a commercial coppersubstrate with carbon coating was used as current collector film 80 andcarbon/tin electrode was attached to carbon coating 92. The sandwichedsample was passed through a gap between a pair of stainless steel rollsheated up to 120° C. for attachment 220. After cooling down to roomtemperature, stack 100A was disassembled. Electrode 95, which initiallywas on copper sacrificial film 90 prior to the hot pressing, wastransferred onto carbon coated substrate 80. Using the tape test, it wasfound that electrode 95 was firmly attached to carbon coated substrate80. Over time, no crumpling or damage of electrode 95 were observed andno delamination was shown, illustrating the stability and flexibility ofstack 100A.

Similarly, cathode stacks 100B may be produced using an electrode slurrycontaining LiCoO₂ as an active material, CMC as the binder, carbon blackas the conductive additive and water as the solvent. The cathode slurrywas coated onto a 15 micron-thick aluminum foil as sacrificial film 90and dried at 80° C. to produce cathode 95. Cathode 95 was thentransferred to a commercial aluminum foil used as current collector film80 having carbon coating 82 on the both sides of the foil using hot rollpress heated up to 80° C. In certain embodiments, anodes 100A andcathodes 100B produced as disclosed herein may exhibit improvedmechanical stability.

FIGS. 4A-4C are high-level schematic illustrations of processes forpreparing various stacks 100 using method 200, according to someembodiments of the invention. FIG. 4A illustrates schematically thepreparation of two stacks 100 simultaneously by applying electrodeslurry to both sides of sacrificial film 90 to produce electrodes 95 onboth sides thereof and then attaching current collector films 80(possibly with coatings 82) to both electrodes 95 simultaneously.Delamination 222 may be synchronous or sequential to yield stacks 100.FIG. 4B illustrates schematically a similar double-sided preparationwith (•••) indicating possible additional layers attached on the othersides of current collector films 80 (possibly with coatings 82),possibly with additional cell components. FIG. 4C illustratesschematically simultaneous production of two double-sided stacks 100,each having current collector films 80 (possibly with coatings 82) withelectrodes 95 on either side thereof. It is noted that in any of theillustrations, current collector films 80, coatings 82, electrodes 95and sacrificial films 90 may be of different kinds in a single process,as long as the relations in binding strength illustrated in FIGS. 3B, 3Care maintained.

In certain embodiments, the surface of one or more of electrodes 95and/or current collector film 80 (when not coated) may be pretreated 105to enhance its adhesion to respective adjacent current collector film 80and/or electrode 95. In certain embodiments, coated films may also bepre-treated to enhance the respective binding to adjacent layer.Achieved adhesion enhancement may improve the integration of therespective layer and provide more uniform and compact cell structures,resulting in improved electrolyte wetting, cell conductivity (e.g.,reduce ESR—equivalent series resistance) and other cell characteristics.For example, plasma treatment 105 may be applied to activate therespective surface(s) prior to pressing the respective layers, toenhance their attachment (e.g., lamination) by resulting electrostaticforces between the activated surface and the layer connected thereto.Surface treatment 105, such as by plasma, may be configured to affectonly the surface and not deteriorating the bulk properties of thetreated layer, and may additionally improve wetting and ionicconductivity of the treated surface.

FIG. 5 is a high-level schematic illustration of stacks 100 havingelectrode(s) and cell separator(s) 75, prepared by method 200, accordingto some embodiments of the invention. FIG. 5 is a highly schematicillustration of multi-stage method 200, which may be implemented withdifferent variations to produce various stacks 100. Layer transferringmay be carried out by layer transfer module 160 of cell stack assemblysystem 150. The term “cell separator” refers to a separator film in anelectrochemical cell or in any other type of energy storage device. Forexample, separator(s) may comprise various materials, such as any ofpolyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET),poly vinylidene fluoride (PVDF) and/or other appropriate materials. Asnon-limiting examples, a polymer membrane such as a polyolefin,polypropylene, or polyethylene membrane, a multi-membrane thereof, amicro-porous film, or a woven or non-woven fabric may be used as theseparator. In certain embodiments, composite separators may be preparedfrom combinations of alumina, zirconia, titania, magnesia, silica andcalcium carbonate along with various polymer components as listed above.

Following attachment 220 of electrode 95 to current collector film 80and delamination 222 of sacrificial film 90 (with respective bindingstrengths (2)>(1)) to form and intermediate stack 100C, as illustratedschematically in FIGS. 3A-3C, a cell separator slurry (prepared using athird solvent which may attack electrode 95 and/or a coating 77 attachedthereto if brought in direct contact with the cell separator slurry) maybe spread onto a sacrificial film 70 and dried thereupon (e.g., byevaporation) to form cell separator 75. Possibly a coating 72 may beapplied to sacrificial film 70 prior to the deposition of the cellseparator slurry to regulate the binding strength (3) there between, andpossibly coating 77 may be applied to electrode 95. At an attachmentstage 260, cell separator 75 may be attached to electrode 95 andsacrificial film 70 may then be delaminated 280 to form stack 100 withcurrent collector film 80, electrode 95 and cell separator 75, possiblywith coatings 82, 77 which regulate conductivity and adhesivenessbetween the layers of stack 100. In particular, the binding strengths(2), (4) between layers of stack 100 are higher that binding strength(3) between cell separator 75 and sacrificial film 70 (and/or itscoating 72) to maintain the stack structure through the attachment anddelamination processes. Attachment and delamination processes 220, 260and 222, 280 respectively, may be configured to enhance thesedifferences in binding strengths, e.g., increase binding strengths (2),(4) and/or reduce binding strengths (1), (3). Application of pressureand possibly heat may be configured accordingly.

In certain embodiments, the surface of separator 75 (and/or possibly ofrespective electrode 95 if not coated) may be pretreated 105 to enhanceits adhesion to respective adjacent electrode 95. Separator pretreatment105 may be similar or different from electrode or current collector filmpretreatment 105. In certain embodiments, coated films may also bepre-treated to enhance the respective binding to adjacent layer.Achieved adhesion enhancement may improve the integration of therespective layer and provide more uniform and compact cell structures,resulting in improved electrolyte wetting, cell conductivity (e.g.,reduce ESR—equivalent series resistance) and other cell characteristics.For example, plasma treatment 105 may be applied to activate therespective surface(s) prior to pressing the respective layers, toenhance their attachment (e.g., lamination) by resulting electrostaticforces between the activated surface and the layer connected thereto.Surface treatment 105, such as by plasma, may be configured to affectonly the surface and not deteriorating the bulk properties of thetreated layer, and may additionally improve wetting and ionicconductivity of the treated surface. It is emphasized that disclosedsurface treatment 105 is configured to enhance the lamination of thelayers and the compactness of the resulting structure, as disclosedherein.

In certain embodiments, surface treatment 105 of separator 75 may beconfigured to create oxygen termination of surface molecules such ascarboxylates, hydroxyls, etc. which may react electrostatically withoxides exposed on the surface of electrode(s) 95 (e.g., anode 95A,cathode 95B) under pressure, when pressed against each other.Consequently, improved integration (or lamination) of separator 75 andelectrode(s) 95 may be achieved.

Surface treatment 105 of separator 75 may be carried out using varioustechnologies, such as plasma, corona, ultraviolet radiation (UV) etc.Surface treatment 105 may be applied a specified period prior toattachment of separator 75 and electrode(s) 95, which is configured tomaintain the required activation of the surface of separator 75, e.g.,maintain its electrostatic activation, a required density of oxygentermini etc.

In certain embodiments, exposed surface features of electrode(s) 95 maysuffice to bind the treated surface of separator 75, e.g., due todefects and/or due to characteristics of the anode active material. Inother embodiments, the surface of electrode(s) 95 may be treated toproviding binding sites to the treated surface of separator 75. Incertain embodiments, the anode active material may comprise metalloidssuch as silicon, germanium and/or tin and separator 75 may comprisecompatible materials such as silica or equivalent oxides, to enhance thebinding capacity of surface-treated separator 75 to electrode(s) 95.

Surface treatment 105 of separator 75 may be incorporated in a range ofcell assembly and stacking techniques, implementing any of winding,stacking and folding of electrodes 95 and separator 75, such as e.g.,single sheet stacking (attaching discrete electrodes 95 and separator 75elements), winding (attaching electrodes 95 and separator 75 in foils,using two separator rolls to fully fold the anodes and cathodes into thestack), Z-folding with single electrodes (discrete electrodes 95 foldedinto separator 75 foil, with separator 75 contacting the anodes atalternating faces thereof), Z-folding with electrode rolls, etc. Surfacetreatment 105 of separator 75 may be configured and applied to one orboth sides of separator 75 and/or possibly at patches thereof configuredto be attached to the anodes and/or to the cathodes, depending on therespective stack assembly process.

Advantageously, in certain embodiments, lamination of lithium batteryelectrodes to standard separators utilizing surface activationtreatments on the separators may be applied without using adhesionpromoters to avoid closing pores in the attached surfaces and therebyavoid increasing the cell resistance. Surface treatment may also beutilized to enhance surface wetting by the electrolyte. Using surfacetreatment to enhance lamination by utilizing electrostatic forcesbetween surface anchoring groups on separator 75 and electrodes 95 maysignificantly improve cell integration and compactness, whilemaintaining low cell resistance.

Method 200 may further comprise attaching a second electrode, possiblyattached to another current collector film (not shown) to cell separator70 along similar process steps as illustrated in FIG. 5, to producestack 100 having an anode and a cathode, each with the correspondingcurrent collector film, separated by a cell separator. Such stack 100may then be used directly to form the electrochemical cell or energystorage device cell.

FIG. 6 is a high-level schematic illustration of using structures 80C ascurrent collector 80, which may be patterned, mesh-like and/or foam-likeaccording to some embodiments of the invention. Structures 80C may beapplicable as any type of current collector 80, 80A, 80B. Structures 80Cmay be patterned in various patterns, comprise a mesh or be mesh-like,comprise a foam or be foam-like, and so forth (two non-limitingexamples, mesh and pattern/foam are illustrated schematically in FIG.6). In some embodiments, structures 80C may be used as current collector80, with the pitch, or characteristic size, and the electrode thicknessbeing optimized for the transfer mechanism described above.

FIG. 6 further illustrates schematically various configurations forusing structures 80C to produce, e.g., one sided electrodes 95 withvariable thickness (T1, T2) or uniform thickness (T1) on structures 80C,and two-sided electrodes 95 with variable thickness (T1, T3) or uniformthickness (for T1=T3) on structures 80C.

Method 200 may further comprise using structures which are patterned,mesh-like and/or foam-like for the current collector (stage 216, in FIG.7), illustrated in FIG. 6 as optionally starting from a uniformstructure 80 and/or optionally applying coating 82 as described above.In certain embodiments, uniform structure 80 may be patterned orotherwise modified (e.g., mechanically or chemically) to providestructures 80C. Electrode 95 may then be coated e.g., by coating 77 andbe further processed (e.g., mechanically or chemically, such as byetching), possibly involving additional deposition and transfer steps toform stack 100.

Advantageously, using patterned, mesh-like and/or foam-like structures80C may improve the access of ions to electrode 95 through open viasprovided by structures 80C, possibly to both sides of electrode 95.Patterned, mesh-like and/or foam-like structures 80C may be particularlyadvantageous in high specific energy thin layer electrodes 95 (e.g.,having thickness, e.g., T1, T2 and/or T3 of any of 10 μm, 20 μm, 50 μm,100 μm, 200 μm, etc.).

In some embodiments, structures 80C may be used either directly ascurrent collector 80 and/or as sacrificial film 70 for transferringelectrodes 95.

In some embodiments, method 200 may be used to coat an adhesion layer ina similar manner as described for electrode 95. Particular advantages ofmethod 200 in case of the adhesion layer result from the very smallthickness of the adhesion layer, which impedes application of theadhesion layer in the prior art.

Certain embodiments comprise stacks 100 described herein, as produced bymethod 200, and electrochemical cells comprising stacks 100. Elementsfrom FIGS. 1-6 may be combined in any operable combination, and theillustration of certain elements in certain figures and not in othersmerely serves an explanatory purpose and is non-limiting.

FIG. 7 is a high-level flowchart illustrating methods 200, according tosome embodiments of the invention. The method stages may be carried outwith respect to stacks 100 described above, which may optionally beconfigured to implement method 200. The stages of method 200 may beimplemented irrespective of their order.

In certain embodiments, method 200 may comprise surface treating thecell separator prior to attachment to at least one electrode (stage180), and configuring the surface treatment to form binding sites on thecell separator and enhance, electrostatically, the binding thereof tothe electrode(s), through the binding sites (stage 184). For example,surface treatment 105 may comprise any of plasma, corona, UV radiation,and/or deposition or sputtering processes (stage 182). Surface treatment105 may be applied on one or both sides of the cell separator(s) (stage186). For example, the cold press lamination is carried out below 50° C.

In certain embodiments, method 200 may further comprise attachinganode(s) and cathode(s) to opposite sides of the separator,simultaneously (stage 190), assembling cell stack(s) by multiple cellseparators, which may be surface-treated on both sides, to correspondingmultiple alternating anodes and cathodes (stage 192) and attaching theelectrode(s) to the separator(s) by cold-press lamination, utilizing theelectrostatic binding sites to stabilize the stack (stage 194). Incertain embodiments, method 200 may comprise carrying out the stackassembly by any of single sheet stacking, winding, Z-folding with singleelectrodes and/or Z-folding with electrode rolls (stage 196).

In various embodiments, method 200 may further comprise integrating anyof separator and/or electrodes surface treatment and cold-presslamination, layer transfer(s) from sacrificial film(s) and face-to-facepressing of anodes into stack production (stage 205).

Method 200 comprises depositing an electrode slurry (comprising a firstsolvent) on a sacrificial film to form an electrode thereupon (stage210), attaching (e.g., laminating) a current collector film (which isproduced at least partly using a second solvent) onto the formedelectrode to yield a stack (stage 220). Any of the components areconfigured so that the binding strength of the electrode to the currentcollector film is higher than the binding strength of the electrode tothe sacrificial film (stage 221). Method 200 may further compriseapplying at least a pressure on the stack to carry out the lamination(and possibly the delamination) (stage 224), e.g., by pressing orcalendaring, optionally also applying heat to carry out the laminationto enhance the binding strength of the cell separator to the electrode.Method 200 further comprises delaminating the sacrificial film from theelectrode while maintaining the attachment of the electrode to thecurrent collector film (stage 222).

Method 200 may comprise, e.g., as implementations of stage 221, any ofcoating the current collector film with a conductive adhesive prior toattaching 220 and/or surface treating the current collector film priorto attaching 220 (stage 212); coating the electrode with a conductiveadhesive such as a carbon coating prior to attaching 220 and/or surfacetreating the electrode prior to attaching 220 (stage 214); and/orcoating the sacrificial film, prior to depositing 210, with a coatinghaving a lower binding strength to the electrode than the bindingstrength of the electrode to the current collector film (stage 218). Incertain embodiments, method 200 further comprises pretreating at leastone side of the electrode (stage 218).

Method 200 may optionally further comprise applying at least a pressureon the stack produced after delamination stage 222 e.g., by pressing orcalendaring, optionally also applying heat and configuring the appliedpressure (and optionally heat) to enhance the binding strength of thecell separator to the electrode (stage 225). In certain embodiments,method 200 may comprise wetting at least one of the electrode and thecurrent collector film to enhance adhesiveness therebetween (stage 228).

In certain embodiments, disclosed methods, stacks and electrochemicalcells implementing any of surface-treated separators, layer transferringusing sacrificial films and/or face-to-face calendaring of the electrodematerial may be combined and integrated to yield flexible and durableelectrode stacks.

FIG. 7 further illustrates a non-limiting example for an electrodeproduction method 200A as part of method 200 disclosed herein, accordingto some embodiments of the invention. The method stages may be carriedout with respect to electrode production system 150 and/or electrodes 95described above, which may optionally be configured to implement method200A. Method 200A may comprise stages for producing, preparing and/orusing electrode production system 150 and/or electrodes 95, such as anyof the following stages, irrespective of their order.

In certain embodiments, method 200 may comprise preparing electrodefoils by pressing (e.g., calendaring) two coated films (e.g., havingcoatings of dried electrode slurry), with the coatings on the filmsfacing each other and pressing each other (stage 230). Method 200 maycomprise configuring the electrode production system to press pairs ofcoated electrode foils against each other, so that the coatings (e.g.,dried electrode slurries) apply forces on each other (stage 232).

In certain embodiments, pressing 210 may be configured to enable and/orcause mass transfer between protrusions and cavities in the filmcoatings (e.g., of the dried electrode slurry layers) to even outsurfaces thereof (stage 234).

Certain embodiments comprise pressing at least two double-sided coatedcurrent collector foils between external coated foils, wherein thecoatings on the double-sided foils face each other and the coatings ofthe respective external foils, and are pressed against each other (stage240). In certain embodiments, the external foils may be disposableand/or be used as sacrificial layers.

In certain embodiments, pressing 210 may be carried out rotationally bycalendaring and/or linearly, e.g., by linear pressing (stage 242). Incertain embodiments, method 200 may further comprise applying heat to atleast one of the foils during the pressing (stage 244).

In certain embodiments, method 200 comprises preparing electrodes fromat least one of the pressed double-sided coated current collector foilsand/or comprises preparing electrodes from at least one of the pressedsingle-sided coated current collector foils (stage 246).

Certain embodiments comprise anode(s) prepared by electrode-preparationmethod 200 and/or electrode production system 150; cathode(s) preparedby electrode-preparation method 200 and/or electrode production system150; and/or lithium ion cell(s) comprising anode(s) and/or cathode(s)prepared by electrode-preparation method 200 and/or electrode productionsystem 150.

Method 200 may comprise consecutively, depositing a cell separatorslurry on a second sacrificial film to form a cell separator thereupon(stage 250), attaching (e.g., laminating) the electrode (which isattached to the current collector film) onto the formed cell separator,to yield a second stack (stage 260), and configuring a binding strengthof the cell separator to the electrode to be higher than a bindingstrength of the cell separator to the second sacrificial film (stage270), e.g., by application of coatings and/or adhesives as disclosedabove to any of the cell separator, the second sacrificial film and/orthe electrode (stage 252). For example, the second sacrificial film maybe coated, prior to the depositing of the cell separator, with a coatinghaving a lower binding strength to the cell separator than the bindingstrength of the cell separator to the electrode. Method 200 may furthercomprise applying at least a pressure on the second stack to carry outlamination (and possibly the delamination) (stage 282), e.g., bypressing or calendaring, optionally also applying heat to carry outlamination to enhance the binding strength of the cell separator to theelectrode. In certain embodiments, method 200 further comprisesPretreating at least one side of the separator (stage 255). Method 200may further comprise delaminating the second sacrificial film from theseparator while maintaining the attachments of the separator to theelectrode and of the electrode to the current collector film (stage280).

Method 200 may optionally further comprise applying at least a pressureon the second stack produced after delamination stage 280 e.g., bypressing or calendaring, optionally also applying heat and configuringthe applied pressure (and optionally heat) to enhance the bindingstrength of the cell separator to the electrode (stage 284).

Method 200 may further comprise using the electrode as at least one ofan anode and a cathode in a cell (stage 290), possibly completing atleast part of the cell assembly. In certain embodiments, the cellseparator may be attached by method 200 to either anode or cathode, andpossibly consecutive attaching may be configured to yield a third stackof anode, cell separator and cathode.

In any of the disclosed embodiments, method 200 may further comprisetreating any one of the attached surfaces (105) to enhance adhesion andimprove the integration of the respective layer and provide more uniformand compact cell structures, resulting in improved electrolyte wetting,cell conductivity (e.g., reduce ESR—equivalent series resistance) andother cell characteristics. For example, electrode surfaces may bepretreated prior to attachments (see e.g., stage 219) and/or separatorsurfaces may be pretreated prior to attachments (see e.g., stage 255).Surface treatment 105, such as by plasma, may be configured to affectonly the surface and not deteriorating the bulk properties of thetreated layer, and may additionally improve wetting and ionicconductivity of the treated surface. In case of the separator, surfacetreatment 105 may be configured to create oxygen termination of surfacemolecules such as carboxylates, hydroxyls, etc. which may reactelectrostatically with oxides exposed on the surface of the electrode(s)under pressure, when pressed against each other.

In certain embodiments, disclosed methods, stacks and electrochemicalcells implementing any of surface-treated separators, layer transferringusing sacrificial films and/or face-to-face calendaring of the electrodematerial may be combined and integrated to yield flexible and durableelectrode stacks.

Electrode-preparation methods and systems are provided, in which coatedfoils, e.g., having dried electrode slurry layers on one or both sidesof current collector films, are pressed against each other, with coatinglayers on the films facing each other and pressing each other.Particularly in lithium ion battery anodes made of metalloid anodematerial particles, the hardness of the particles may provide moreefficient pressing when pressed against each other, than when pressed byan external calendar—leading to thinner, smother and more controllablyporous electrodes and higher throughput. Two or more double-sided coatedcurrent collector foils may be pressed between external (possiblysacrificial) coated foils, with the coatings on the double-sided foilsface each other and the coatings of the respective external foils.Electrodes (e.g., anodes, cathodes) may be prepared from the presseddouble-sided coated current collector foils.

FIG. 8 is a high-level schematic illustration of electrode foils 110 andpressing and/or calendaring unit 170 in electrode production system 150,according to some embodiments of the invention. Coated current collectorfoils 101, composed of a current collector film 104 and coating 102 onat least one side of film 104, are pressed against each other to yieldelectrode foils 110 with smooth surfaces 112. Electrode(s) 95 may thenbe processed from electrode foils 110. FIG. 9 is a high-level schematicillustration of prior art electrode production 50. In the prior art,slurry 62 is applied to a film 60 and pressed by calendar 55 intoelectrode 65. In the prior art, at least one of calendars 55 presses thesurface of the coating directly. The inventors have found out and showbelow, that applying pressure by one coating 102 on a facing coating 102provides smoother resulting coatings 112 (with respect to a surfaceroughness 67 of prior art electrode foils 65, see e.g., FIGS. 17A, 17B),with improved quality and better operation as electrodes in lithium ionbatteries. It is noted that spaces between foils and system elements areshown merely for illustration and clarity purposes, as foils pressedagainst each other contact each other. Any of the embodiments may beimplemented by pressing or calendaring unit 170, possibly as part ofvarious embodiments of electrode production system 150.

Electrode production systems 150 comprise two pressure-applyingapparatuses 115 (e.g., rotational calendars, linear presses, etc.)facing each other and configured to receive and press, against eachother, at least two coated current collector foils 101 having, e.g.,dried electrode slurry layers 102 as coatings on current collector films104. It is noted that dried electrode slurry coating 102 of currentcollector films 104 may be configured to optimize mechanical parametersof the process and the resulting characteristics of produced electrodefoils 110.

In contrast to prior art, pressure-applying apparatuses 115 applypressure indirectly to coatings 102, as pressure-applying apparatuses115 press directly films 104 and not slurry layers 102. The actualforces applied onto coatings 102, such as a longitudinal force 125 and aperpendicular force 120 illustrated schematically in FIG. 8, are appliedupon contact of coating layer 102 with the other coating layer 102,while neither coating layer 102 contacts pressure-applying apparatuses115.

The inventors have found out that avoiding direct contact ofpressure-applying apparatuses 115 with coatings 102, and moreover, theinterlayer force application, contribute to forming thinner, smootherand possibly more uniform electrodes foils 110. The porosity ofelectrodes foils 110 may be better controlled by the disclosed processesas well. Finally, the throughput of electrode production system 150 ofFIG. 8 may be double with respect to prior art electrode production 80illustrated in FIG. 9.

FIG. 10 is a high-level schematic illustration of electrode productionsystem 150, according to some embodiments of the invention. In certainembodiments, the inventors have found out that mass transfer 122 mayoccur as result of the disclosed pressing, e.g., due to application offorces 120, 125 between coating layers 102. In particular, the inventorshave found out that mass transfer 122 may contribute to evening outprotrusions 102A and/or cavities 102B of coatings 102, e.g., by masstransfer 122 from the former to the latter as well as by theapplications horizontal and vertical evening forces 125, 120,respectively. In particular, hard anode material particles as disclosedabove may be moved by forces 120, 125 to yield smoother electrode foils110, with evened-out surfaces. Adherence of moved coating mass (e.g.,dried electrode slurry mass) during the pressing may be achieved byinteraction of material in coating layers 102 such as anode materialparticles, binder material, polymer material, conductive additives,etc., as well as by the pressing itself through pressure-applyingapparatuses 115 and resulting vertical and horizontal forces 120, 125.

FIGS. 11A and 11B are high-level schematic illustrations of electrodeproduction systems 150, according to some embodiments of the invention.In certain embodiments, at least two double-sided coated currentcollector foils 103 (each comprising current collector films 104 andcoatings 102 on both sides thereof) may be pressed between externalcoated foils 101 (each comprising films 104 and coatings 102 on one sidethereof). Coatings 102 on double-sided foils 103 face each other andcoatings 102 of respective external foils 101, and are pressed againsteach other. The pressing by pressure-applying apparatuses 115 formselectrode foils 110A, 110B from coated foils 101, 103, respectively.

In certain embodiments, electrode production system 150 may beconfigured to handle one (FIG. 14), two (FIG. 17A), three (FIG. 17B), ormore double-sided coated current collector foils 103 and press foils110A therefrom. In certain embodiments, multiple one-sided foils 101and/or double-sided foils 103 may be pressed simultaneously, with one ormore pairs of coating layers 102 pressed against each othertherebetween.

Any of foils 110A, 110B, pressed from foils 101, 103, may be used toprepare electrodes (e.g., anodes, cathodes) by further processing (e.g.,cutting and packaging). It is noted that any one of foils 101, 103 maybe disposable and used as a sacrificial film in the process. Inparticular, one-sided foils 101 may be used as disposable or reusablesacrificial films.

FIGS. 12-16 are high-level schematic illustrations of electrodeproduction systems 150, according to some embodiments of the invention.Systems 150 are shown schematically as comprising spools and rollers 106for handling multiple foils 101, 103, 110 to provide industrialproduction processes using pressure-applying apparatuses 115 toimplements disclosed embodiments. FIGS. 12-16 illustrate schematically,in a non-limiting manner, various production embodiments. It is notedthat spaces between foils and system elements are shown merely forillustration and clarity purposes, as foils pressed against each othercontact each other. It is further noted that in any of the disclosedembodiments, heat may be applied during the pressing of coated currentcollector foils 101, 103 against each other, by any of several means(e.g., direct heat, convective heat, radiative heat, etc.). Moreover, itis noted that that in any of the disclosed embodiments, processparameters such as thickness of the films and coatings, dimensions andparameters of pressure-applying apparatuses 115, operation speed andother parameters of spools and rollers 106, characteristics of heatapplication etc. may be adjusted according to specified requirements.

FIG. 12 illustrates schematically calendaring two one-sided foils 101with their coatings 102 facing each other, similarly to embodimentsillustrated schematically in FIGS. 8 and 10. FIG. 13 illustratesschematically calendaring one-sided foil 101 and double-sided foil 103(having coatings 102 on both sides of film 104) with coating 102 of foil101 facing one of coatings 102 of double-sided foil 103 and pressedagainst it. In certain embodiments, one-sided foil 101 or double-sidedfoil 103 may be sacrificial foils. In certain embodiments, double-sidedfoil 103 may be further processed with respect to coating 102 facingpressure-applying apparatuses 115, possibly using another one-sided foil101, or coating 102 facing pressure-applying apparatuses 115 may be leftwithout further pressing. Respective electrode foils 110, 110A, 110B maybe formed by the disclosed embodiments of the pressing or calendaring.

FIG. 14 illustrates schematically calendaring two-sided foil 101 (havingcoatings 102 on both sides of film 104) between two one-sided foils 103(having coatings 102 on the sides of film 104 that face coating 102 oftwo-sided foil 101). Respective electrode foils 110A, 110B may be formedby the disclosed embodiments of the pressing or calendaring.

FIGS. 15 and 16 illustrate schematically the use of linearly operatingpresses 115 as pressure-applying apparatuses 115, applicable in systems150 in place of, or in addition to, rotationally operating calendars 115illustrated e.g., in FIGS. 12-14. One-sided foils 103 (having coating102 on one side of film 104) and/or two-sided foil 101 (having coatings102 on both sides of film 104) may be pressed between external one ortwo one-sided foils 101 (or possibly one or two two-sided foils 101, seee.g., FIG. 13), which may be disposable or reusable as sacrificiallayers. For example, FIG. 15 illustrates schematically using one-sidedfoil 101 as sacrificial layer (bottom layer) when pressing anotherone-sided foil 101 (top layer), while FIG. 16 illustrates schematicallyusing two one-sided foils 101 as sacrificial layers when pressing onetwo-sided foil 103.

It is noted that in FIGS. 8 and 11-16, spaces between layers 102 thatare pressed against each other and spaces between pressure-applyingapparatuses 115 and films 104—are shown only for clarity reasons (crosssection shown in exploded view), as clearly the pressing involvescontact between the respective structures.

In certain embodiments, systems 150 may comprise members configured tosurface-treat at least one separator film and to attach thesurface-treated separator to at least one of the coated foils, which maybe coated e.g., with electrode slurry, and attached to the separator(s)at their treated surface(s), as illustrated e.g., in FIGS. 1A, 1B.

FIGS. 17A and 18A illustrate examples of cross-sections of prior artelectrode foils 65, while FIGS. 17B and 18B illustrate examples ofcross-sections of electrode foils 110 prepared according to someembodiments of the invention. The illustrated examples were imaged byscanning electron microscope (SEM).

As an example for the improved quality of one-sided electrode foils 110,FIG. 17B illustrates a cross-section of one-sided electrode foil 110prepared by pressure-applying apparatuses 115 as explained above,according to some embodiments of the invention, with respect to FIG. 17Aillustrating a cross-section of prior art one-sided electrode foil 65.Electrode foil 110 is clearly flatter, thinner and has smother surface112 (with respect to prior art surface 67) and may have a more uniforminternal structure with better controllable porosity than prior artelectrode foils 65.

As another example for the improved quality of double-sided electrodefoils 110, FIG. 18B illustrates a cross-section of double-sidedelectrode foil 110 prepared by pressure-applying apparatuses 115 asexplained above, according to some embodiments of the invention, withrespect to FIG. 18A illustrating a cross-section of prior artdouble-sided electrode foil 65. Electrode foil 110 is clearly flatter,thinner and has smother surface 112 (with respect to prior art surface67) and may have a more uniform internal structure with bettercontrollable porosity than prior art electrode foils 65.

FIGS. 19A-19C are examples for disclosed separators 75 and stacks 108prepared according to disclosed methods 200, compared to prior artseparators and stacks. FIG. 19A is an image of laminate stack 108,according to some embodiments of the invention. Laminate stack 108 isthin and uniform, having good and stable attachment of separator 75 andelectrodes 95. FIG. 19B is a comparison of laminated stack 108 withprior art stack 68 in which cathode foil 68 is not attached well tountreated separator 61. FIG. 19C demonstrates the better wettability ofsurface-treated separator 75 by the electrolyte, measured by the sessiledrop method, according to some embodiments of the invention, withrespect to untreated separator 61. The better wettability indicates thesurface activation of separator 75 which enables it to attach toelectrodes 95 as disclosed below, as well as improving its wettabilitytowards the electrolyte.

In the non-limiting illustrated examples of FIGS. 19A-19C, apolyethylene membrane film having a monolayer architecture with athickness of 12 microns and about 41% porosity was used as theseparator, the anode was based on Ge anode material, coated on a Cu filmas current collector to form a layer ca. 20 μm thick. The cathode wasbased on NCA coated on Al film and having a thickness of about 50 μm.The separator membrane and electrodes were treated in an Ar or dry airmicrowave plasma applicator under different conditions, e.g., 18 Wapplied for 1-3 minutes. Right after plasma treatment, the separator andelectrodes were laminated under dry air environment (dew point −40° C.).Cold lamination was performed using a two-roll calendar tool attemperatures below 55° C., and resulted in a strong bond between theelectrodes and separator, as illustrated in FIG. 19A while untreatedseparator films, under the same stacking and process conditions, did notyield stable attachment to the electrodes (FIG. 19B). No changes in thestacking (bonding) of the laminated electrodes and separator afterplasma treatment were observed after ten days stored under airenvironment. The laminated and non-laminated electrodes and separatorswere closed to soft pack pouch cells with EMC-based electrolyte. Thelaminated cells showed increased cycle life under high charging rates,as illustrated below (see FIGS. 22A-22C).

It is noted that the plasma treatment bay be carried out under differentconditions, which may be adjusted and optimized with respect to eachother and according to the materials used in the batteries, e.g., thepower and duration of surface treatment 105 may vary in the ranges10-600 W power for 1000-10 seconds, respectively (the higher the appliedpower is, the shorter is the duration of the surface treatment).

FIG. 19D is a SEM image of prior art double sided electrode (anode)produced not using the disclosed lamination process, and exhibitingrough and non-uniform anode surfaces.

FIGS. 20A and 20B are SEM images of prepared laminated separators 75 andelectrodes 95, according to some embodiments of the invention. FIG. 20Aillustrates laminated cathode 95B, separator 75 and anode 95A, and FIG.20B illustrates pairs of laminated anode 95A and separator 75, andcathode 95B separator 75—all of which indicating the production qualityof laminated stacks 108. As illustrated in the SEM images, electrodes 95are uniform and thin, and are uniformly and securely attached toseparator 75.

FIG. 21 provides SEM images of the surfaces of anode 95A, cathode 95Band separator 75, respectively, before and after surface treatment 105by plasma, in a non-limiting example, according to some embodiments ofthe invention. No surface damage or other surface morphology changeswere observed on the separator and electrodes after the plasmatreatment. Energy-dispersive X-ray spectroscopy showed oxygentermination on the surface such as carboxylates, hydroxyls, etc. asdisclosed above, serving as binding sites 105A on separator 75 and/orsurface elements 105B on electrodes 95 during the lamination process, toyield improved laminated stacks 108.

FIGS. 22A-22C illustrate prior art cell assembly with its cyclingcharacteristics and cycling characteristics of laminated stacks 108illustrated in FIG. 19A, in a non-limiting example, according to someembodiments of the invention. Laminated stacks 108 were prepared bylaminating an anode, a separator, and a cathode using the calendaringprocedure after plasma surface pretreatment and assembling the stackinto a soft package pouch cell with EMC-based electrolyte. The prior artstack illustrated in FIG. 22A was prepared without plasma pretreatment,attaching the anode, separator, and cathode without plasma pretreatment,by sticking the electrodes and separator together with a glue stripduring cell assembly. An additional prior art stack assembly was carriedout without plasma pretreatment and without additional attaching of theelectrodes and separator, which resulted in cells with very highinternal resistance onto which fast charging (at 8 C) was not applicableat all. In the prior art cells, the same EMC-based electrolyte was used.All cells were run at a standard procedure of formation and cycled at 8C/1 C charging/discharging rates. FIGS. 22B and 22C illustrate thecycling characteristics of the prior art stack of FIG. 22A and oflaminated stack 108 of FIG. 19A, respectively. The cyclingcharacteristics comprise the charged and discharged capacities, Columbicefficiency (cycling efficiency) and capacity retention form the initialvalue Similar behavior of two cells is observed, clearly indicating theefficiency and compatibility of surface treatment and cold laminationdescribed above, and provide improved cycling efficiency and capacityretention with respect to the prior art cells.

Disclosed electrode foils 110 may be used as anodes in energy storagedevices, such as lithium ion batteries. The electrode slurry, andconsequently coatings 102 and electrode foils 110, may comprise anodematerial in form of anode material particles (e.g., having a diameter of100-500 nm), which may comprise e.g., particles of metalloids such assilicon, germanium and/or tin, and/or possibly particles of aluminum,lead and/or zinc, and may further include various particle surfaceelements (e.g., having a diameter of 10-50 nm or less) suchnanoparticles (e.g., B₄C, WC, VC, TiN), borate and/or phosphate salt(s)and/or nanocrystals and possibly polymer coatings (e.g., conductivepolymers, lithium polymers). The electrode slurry may be prepared byball milling processes and may further comprise additive(s) such asbinder(s), plasticizer(s) and/or conductive filler(s). Drying of slurryspread on film 104 to form dried slurry layer(s) 102 may be carried outmay be carried out with or without further intervention, the formerpossibly involving controlling environmental conditions (e.g.,temperature, humidity), applying direct heat or air flow and/orcontrolling evaporation parameters.

Without being bound by theory, the inventors suggest that the thinnerand more uniform electrodes 110 may be a result of forces 120, 125acting between the anode material particles in each electrode 110 andbetween electrodes 110, respectively, instead of between electrode 65and calendar 55 as in the prior art. For example, the direct applicationof forces among anode material particles in dried slurry layers 102,being pressed against each other, may yield a smoother surface ofelectrodes 110 by evening out the surface more efficiently than bypressing against the large external calendar 55 of the prior art (e.g.,larger, or more effectively applied forces 125). Moreover, as in someembodiments, the anode material particles have a higher strength thanthe material of prior art calendar 55 (e.g., Si/Ge anode materialparticles with B₄C/WC nanoparticles or coatings versus aluminum of priorart calendar 55) larger forces may be applied in the disclosed inventionthan in the prior art, possibly leading to more efficient smoothing(e.g., larger forces 120). In certain embodiments, the similarcomposition of dried slurry layers 102 being pressed against eachother—may yield a smoother and/or more uniform product electrode 110than resulting from prior art asymmetry between pressed film 60 andpressing calendar 55, which are typically made of different materialsand have different structural parameters and characteristics.

Advantageously, disclosed method 200 and systems 150, in any of theirembodiments and/or combinations, may provide improved electrodes, whichare more uniform (in bulk and/or on their surface) and operate better inlithium ion cells. For example, electrode foils 110 may have fewerand/or less sharp protrusions 102A, reducing the probability for chargeaccumulation at the protrusions), have a more uniform thickness,reducing the expansion of the electrode during the charging cycles.Moreover, the better adhesion and uniformity achieved through disclosedmethods 200 and systems 150 also reduce the resistance of the electrodeand therefore improve the cell's performance.

In the above description, an embodiment is an example or implementationof the invention. The various appearances of “one embodiment”, “anembodiment”, “certain embodiments” or “some embodiments” do notnecessarily all refer to the same embodiments. Although various featuresof the invention may be described in the context of a single embodiment,the features may also be provided separately or in any suitablecombination. Conversely, although the invention may be described hereinin the context of separate embodiments for clarity, the invention mayalso be implemented in a single embodiment. Certain embodiments of theinvention may include features from different embodiments disclosedabove, and certain embodiments may incorporate elements from otherembodiments disclosed above. The disclosure of elements of the inventionin the context of a specific embodiment is not to be taken as limitingtheir use in the specific embodiment alone. Furthermore, it is to beunderstood that the invention can be carried out or practiced in variousways and that the invention can be implemented in certain embodimentsother than the ones outlined in the description above.

The invention is not limited to those diagrams or to the correspondingdescriptions. For example, flow need not move through each illustratedbox or state, or in exactly the same order as illustrated and described.Meanings of technical and scientific terms used herein are to becommonly understood as by one of ordinary skill in the art to which theinvention belongs, unless otherwise defined. While the invention hasbeen described with respect to a limited number of embodiments, theseshould not be construed as limitations on the scope of the invention,but rather as exemplifications of some of the preferred embodiments.Other possible variations, modifications, and applications are alsowithin the scope of the invention. Accordingly, the scope of theinvention should not be limited by what has thus far been described, butby the appended claims and their legal equivalents.

1. A method comprising: surface treating at least one cell separatorprior to attachment to at least one electrode, wherein the surfacetreating is configured to form binding sites on the at least one cellseparator, and attaching the at least one cell separator to the at leastone electrode by cold press lamination, wherein the created bindingsites are configured to stabilize the cold press laminationelectrostatically.
 2. The method of claim 1, further comprising applyingthe surface treatment to both sides of the at least one cell separatorand wherein the at least one electrode comprises, for each of the atleast one cell separator, an anode attached to one side of the separatorand a cathode attached to another side of the separator.
 3. The methodof claim 2, wherein both anode and cathode are attached to the separatorsimultaneously.
 4. The method of claim 2, further comprising assemblinga cell stack by performing the attachment to a plurality of cellseparator and a corresponding plurality of alternating anodes andcathodes.
 5. A flexible battery comprising the assembled cell stackprepared by the method of claim
 4. 6. The method of claim 1, wherein thecold press lamination is carried out below 60° C. and/or below 40 and/orat room temperatures.
 7. The method of claim 1, wherein the surfacetreatment is carried out by any of plasma treatment, corona treatment,ultraviolet radiation.
 8. The method of claim 1, wherein the surfacetreatment is carried out by depositing an ionic-conductive surface layerto form the binding sites.
 9. The method of claim 1, wherein the atleast one cell separator is polymeric and the surface treatmentcomprises depositing a ceramic surface layer onto the polymeric at leastone cell separator.
 10. The method of claim 1, wherein the at least oneelectrode comprises attached corresponding at least one currentcollector film.
 11. The method of claim 10, wherein the at least oneelectrode is attached to the corresponding at least one currentcollector film by a conductive adhesive.
 12. The method of claim 1,wherein the attaching is carried out using a sacrificial film onto whichat least one of: at least one cell separator and the at least oneelectrode, are deposited as corresponding slurry.
 13. The method ofclaim 1, further comprising pressing the at least one electrodeface-to-face against another electrode prior to the attaching of the atleast one cell separator.
 14. The method of claim 1, wherein theattaching is carried out by at least one of: single sheet stacking,winding, Z-folding with single electrodes and Z-folding with electroderolls.
 15. The method of claim 1, further comprising: prior to thesurface treatment, depositing a cell separator slurry on a sacrificialfilm to form a cell separator thereupon, and following the surfacetreatment: attaching the formed cell separator onto the at least oneelectrode attached to at least one corresponding current collector film,to yield a stack, wherein a binding strength of the cell separator tothe electrode is higher than a binding strength of the cell separator tothe sacrificial film, and delaminating the sacrificial film from theseparator while maintaining the attachments of the separator to theelectrode and of the electrode to the current collector film.
 16. Themethod of claim 15, further comprising preparing the at least oneelectrode attached to the at least one corresponding current collectorfilm by: depositing an electrode slurry on a sacrificial film to formthe at least one electrode thereupon, wherein the electrode slurrycomprises a first solvent, attaching a current collector film, which isproduced using a second solvent, onto the formed electrode, to yield astack, wherein a binding strength of the electrode to the currentcollector film is higher than a binding strength of the electrode to thesacrificial film, and delaminating the sacrificial film from theelectrode while maintaining the attachment of the electrode to thecurrent collector film.
 17. The method of claim 16, further comprising:pressing at least two double-sided coated current collector foilsbetween external coated foils, wherein the coatings on the double-sidedfoils comprise the electrode slurry and face each other and the coatingsof the respective external foils, and are pressed against each other,and preparing the electrodes from at least one of the presseddouble-sided coated current collector foils.
 18. The method of claim 16,further comprising preparing the at least one electrode attached to theat least one corresponding current collector film by: pressing at leasttwo double-sided coated current collector foils between external coatedfoils, wherein the coatings on the double-sided foils comprise electrodeslurry and face each other and the coatings of the respective externalfoils, and are pressed against each other, and preparing electrodes fromat least one of the pressed double-sided coated current collector foils.19. A cell stack assembly system comprising: a surface treatment moduleconfigured to treat both surfaces of each of a plurality of cellseparators, to form binding sites thereupon, a stacking moduleconfigured to stack a plurality of alternating anodes and cathodesbetween the cell separators, and a cold-press lamination moduleconfigured to cold-press the stack, wherein the formed binding sites areconfigured to stabilize the cold-pressed stack electrostatically. 20.The cell stack assembly system of claim 19, further comprising at leastone of: a layer transfer module configured to prepare the at least oneelectrode attached to at least one corresponding current collector filmby depositing an electrode slurry on a sacrificial film to form the atleast one electrode thereupon, wherein the electrode slurry comprises afirst solvent; attaching a current collector film, which is producedusing a second solvent, onto the formed electrode, wherein a bindingstrength of the electrode to the current collector film is higher than abinding strength of the electrode to the sacrificial film; anddelaminating the sacrificial film from the electrode while maintainingthe attachment of the electrode to the current collector film, and acalendaring unit comprising two pressure-applying apparatuses facingeach other and configured to receive and press, against each other, atleast two double-sided coated current collector foils between externalcoated foils, wherein the coatings on the double-sided foils face eachother and the coatings of the respective external foils, and are pressedagainst each other, and wherein the two pressure-applying apparatusesare configured to apply pressure on the external coated foils.
 21. Acell stack for lithium ion batteries, the cell stack comprising aplurality of anodes and cathodes, separated by a plurality of cellseparators, wherein at least one of the anodes, the cathodes and thecell separators are surface treated to form binding sites upon surfacesthereof, and wherein the anodes, the cathodes and the cell separatorsare attached by cold press lamination, electrostatically stabilized bythe created binding sites.
 22. A method comprising: surface treating,prior to stack lamination, at least one cell separator and/or at leastone electrode, wherein the surface treating is configured to formbinding sites on the at least one cell separator and/or at least oneelectrode, respectively, and laminating, by cold press lamination, astack of multiple alternating separators and electrodes, comprising theat least one separator and the at least one electrode, at least one ofwhich being surface treated by said surface treating, wherein thecreated binding sites are configured to stabilize the cold presslamination electrostatically.
 23. The method of claim 22, furthercomprising attaching the alternating separators and electrodes by atleast one of: single sheet stacking, winding, Z-folding with singleelectrodes and Z-folding with electrode rolls.
 24. The method of claim22, wherein the surface treatment is carried out by any of plasmatreatment, corona treatment, ultraviolet radiation.
 25. The method ofclaim 22, wherein the stack of multiple alternating separators andelectrodes comprises at least one of: a single separator and a singleelectrode, a single separator and two electrodes on either side thereof,a single electrode and two separators on either side thereof, analternating plurality of separators and plurality of electrodes.
 26. Themethod of claim 22, wherein the stack of multiple alternating separatorsand electrodes comprises a single separator foil and two electrodesfoils which are laminated to on either side of the separator foil by aroll to roll process.